Planck Early Results. II. The thermal performance of Planck

TitrePlanck Early Results. II. The thermal performance of Planck
Type de publicationJournal Article
Year of Publication2011
AuteursCollaboration}, {Planck, Ade P. a. R., Aghanim N., Arnaud M., Ashdown M., Aumont J., Baccigalupi C., Baker M., Balbi A., Banday A. J., et al.
JournalAstronomy & Astrophysics
Volume536
PaginationA2
Date Publishedjan
ISSN0004-6361
Résumé

The performance of the Planck instruments in space is enabled by their low operating temperatures, 20K for LFI and 0.1K for HFI, achieved through a combination of passive radiative cooling and three active mechanical coolers. The scientific requirement for very broad frequency coverage led to two detector technologies with widely different temperature and cooling needs. Active coolers could satisfy these needs; a helium cryostat, as used by previous cryogenic space missions (IRAS, COBE, ISO, Spitzer, AKARI), could not. Radiative cooling is provided by three V-groove radiators and a large telescope baffle. The active coolers are a hydrogen sorption cooler (<20K), a 4He Joule-Thomson cooler (4.7K), and a 3He-4He dilution cooler (1.4K and 0.1K). The flight system was at ambient temperature at launch and cooled in space to operating conditions. The HFI bolometer plate reached 93mK on 3 July 2009, 50 days after launch. The solar panel always faces the Sun, shadowing the rest of Planck, andoperates at a mean temperature of 384K. At the other end of the spacecraft, the telescope baffle operates at 42.3K and the telescope primary mirror operates at 35.9K. The temperatures of key parts of the instruments are stabilized by both active and passive methods. Temperature fluctuations are driven by changes in the distance from the Sun, sorption cooler cycling and fluctuations in gas-liquid flow, and fluctuations in cosmic ray flux on the dilution and bolometer plates. These fluctuations do not compromise the science data.

URLhttp://arxiv.org/abs/1101.2023 http://www.aanda.org/10.1051/0004-6361/201116486
DOI10.1051/0004-6361/201116486